ISO 6851:2001

INTERNATIONAL ISO
STANDARD 6851
Second edition
2001-12-15
Photography — Processing waste —
Determination of total amino nitrogen
(microdiffusion Kjeldahl method)
Photographie — Effluents de traitement — Détermination de l'azote amino
total (méthode de microdiffusion Kjeldahl)
Reference number
ISO 6851:2001(E)
©
ISO 2001

---------------------- Page: 1 ----------------------
ISO 6851:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2001 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 6851:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Principle.2
4 Reactions.2
5 Safety and operational precautions.2
6 Materials and reagents.3
7 Apparatus .6
8 Sampling and sample preparation.6
9 Procedure .7
10 Expression of results .8
11 Test report .9
Bibliography.10
© ISO 2001 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 6851:2001(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 6851 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 6851:1987), of which it constitutes a technical
revision.
iv © ISO 2001 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 6851:2001(E)
Introduction
This International Standard is one of a series devoted to the analysis of photographic wastes; it encompasses the
field of analysis of the total amino nitrogen (microdiffusion Kjeldahl method) in a photographic effluent.
This International Standard is intended for use by individuals with a working knowledge of analytical techniques.
Some of the procedures use caustic, toxic or otherwise hazardous chemicals. Safe laboratory practice for the
handling of chemicals requires the use of safety glasses or goggles and, in some cases, other protective apparel
such as rubber gloves, face masks or aprons. Normal precautions for the safe performance of any chemical
procedure must be exercised at all times, but specific details have been provided for hazardous materials. Hazard
warnings are designated by a letter enclosed in angle brackets "���." These are defined in clause 5 and then used
throughout the text. More detailed information on hazards, handling and use of these chemicals may be available
from the manufacturer.
Photographic laboratories can establish conformity to effluent regulations only by chemical analysis. If this cannot
be done in-house, an outside laboratory should be used.
© ISO 2001 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 6851:2001(E)
Photography — Processing waste — Determination of total amino
nitrogen (microdiffusion Kjeldahl method)
1 Scope
This International Standard specifies a method for the determination of the total organic nitrogen, as well as any
ammoniacal nitrogen, present in photographic processing wastes by the Kjeldahl method.
Total Kjeldahl nitrogen can be determined in photographic processing wastes in the range of 10 mg/l to 200 mg/l as
ammonia, or in the range of 8 mg/l to 160 mg/l in terms of nitrogen. If ammoniacal nitrogen (see ISO 6853) is
determined separately and subtracted, the concentration of organic amino nitrogen can be established.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 648:1977, Laboratory glassware — One-mark pipettes.
ISO 1042:1998, Laboratory glassware — One-mark volumetric flasks.
ISO 5667-1:1980, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes.
ISO 5667-2:1991, Water quality — Sampling — Part 2: Guidance on sampling techniques.
ISO 5667-3:1994, Water quality — Sampling — Part 3: Guidance on the preservation and handling of samples.
ISO 6353-1:1982, Reagents for chemical analysis — Part 1: General test methods.
ISO 6353-2:1983, Reagents for chemical analysis — Part 2: Specifications — First series.
ISO 6353-3:1987, Reagents for chemical analysis — Part 3: Specifications — Second series.
ISO 6853:2001, Photography — Processing waste — Determination of ammoniacal nitrogen (microdiffusion
method).
ISO 10349-1:1992, Photography — Photographic-grade chemicals — Test methods — Part 1: General.
© ISO 2001 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 6851:2001(E)
3Principle
In the presence of sulfuric acid and/or potassium sulfate with mercuric sulfate as a catalyst, the amino nitrogen of
most organic substances is converted into ammonium hydrogen sulfate. The ammonia is then liberated by
treatment with a suitable alkali and absorbed into a solution of boric acid. The liberation and absorption of the
ammonia is carried out in a microdiffusion cell. The ammonia absorbed into the boric acid is then determined by
titration with standard sulfuric acid.
4 Reactions
...NH
2
...NHR + H SO � (NH )HSO
2 4 4 4
...NR
2
� 2�
(NH )HSO +2OH � NH +2H O+SO
4 4 3 2 4
5 Safety and operational precautions
5.1 Hazard warnings
Some of the chemicals specified in the test procedures are caustic, toxic or otherwise hazardous. Safe laboratory
practice for the handling of chemicals requires the use of safety glasses or goggles, and in some cases other
protective apparel such as rubber gloves, face masks and aprons. Specific danger notices are given in the text for
particularly dangerous materials, but normal precautions are required during the performance of any chemical
procedure at all times.
The first time that a hazardous material is noted in the procedures, the hazard will be indicated by the word
"DANGER" followed by a symbol consisting of angle brackets "��" containing a letter that designates the specific
hazard. A double bracket "��� ��" will be used for particularly perilous situations. In subsequent statements involving
handling of these hazardous materials, only the hazard symbol consisting of the brackets and letter(s) will be
displayed. Furthermore, for a given material, the hazard symbols will be used only once in a single paragraph.
Hazard warning symbols will not be used for common organic solvents when used in quantities of less than 1 litre,
unless they are particularly hazardous.
Detailed warnings for handling chemicals and their diluted solutions are beyond the scope of this International
Standard.
Employers shall provide training and health and safety information in conformance with legal
requirements.
The hazard code system used in this International Standard is intended to provide information to the users and is
not meant for compliance with any legal requirements for labelling, as these vary from country to country.
It is strongly recommended that anyone using these chemicals obtain pertinent information from the
manufacturer about the hazards, handling, use and disposal of these chemicals.
5.2 Hazard information code system
�B� Harmful if inhaled. Avoid breathing dust, vapour, mist or gas. Use only with adequate ventilation.
2 © ISO 2001 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 6851:2001(E)
�C� Harmful if contact occurs. Avoid contact with eyes, skin or clothing. Wash thoroughly after handling.
�F� Will burn. Keep away from heat, sparks and open flame. Use with adequate ventilation.
�O� Oxidizer. Contact with other material may cause fire. Do not store near combustible materials.
�S� Harmful if swallowed. Wash thoroughly after handling. If swallowed, obtain medical attention immediately.
��S�� May be fatal if swallowed. If swallowed, obtain medical attention immediately.
5.3 Safety precautions
ALL PIPETTE OPERATIONS SHALL BE PERFORMED WITH A PIPETTE BULB OR PLUNGER PIPETTE. THIS
IS A CRITICAL SAFETY WARNING!
Safety glasses shall be worn for all laboratory work.
6 Materials and reagents
6.1 General
6.1.1 Handling and labelling
Reagents shall be handled in conformity with health and safety precautions as shown on containers, or as given in
other sources of such information. Proper labelling of prepared reagents includes the chemical name, date of
preparation, expiration date, restandardization date, name of preparer, and adequate health and safety
precautions. The discharge of reagents shall conform to applicable environmental regulations.
6.1.2 Purity
Reagents used in the test procedures shall be certified reagent-grade chemicals and shall meet appropriate
standards, or be chemicals of a purity acceptable for the analysis. For details, see ISO 6353-1, ISO 6353-2 and
ISO 6353-3.
6.1.3 Water
Whenever water is specified without other qualifiers in the test procedures, only distilled water or water of
equivalent purity shall be used.
6.1.4 Strength of solutions
6.1.4.1 Acids and ammonium hydroxide are full strength unless otherwise specified.
6.1.4.2 When a standardized solution is required, its amount-of-substance concentration is expressed in moles
per litre. The number of significant figures to which the molarity is known shall be sufficient to ensure that the
reagent does not limit the reliability of the test method.
6.1.4.3 When a standardized solution is not required, its concentration is expressed in grams per litre (g/l) to
the appropriate number of significant figures.
6.1.4.4 When a solution is to be diluted, its dilution is indicated by (X + Y), meaning that X volumes of reagent,
or concentrated solution, are to be diluted with Y volumes of water (6.1.3).
© ISO 2001 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 6851:2001(E)
6.2 Reagents
6.2.1 Acidified mercury(II) sulfate/potassium sulfate solution (DANGER: ��C�����S��), �(HgO) = 2 g/l,
�(K SO ) = 134 g/l.
2 4
Weigh 134 g� 0,1 g of potassium sulfate, K SO , and transfer it quantitatively to a 1 litre volumetric flask
2 4
conforming to Class A of ISO 1042. Add about 650 ml of water and dissolve the potassium sulfate. Carefully add
200 ml of sulfuric acid, H SO (DANGER: ��C��) � � 1,84 g/ml, from a graduated measuring cylinder and mix.
2 4
1�
Weigh 2 g� 0,1 g of red mercury(II) oxide, HgO (DANGER:���B�����C�����S��), and dissolve it in 25 ml of 3 mol/l
sulfuric acid solution (6.2.4) (DANGER: �C�) in a small beaker. Add the contents of the beaker to th
...